Multitasking of a modern smartphone often requires having several numbers: one for personal calls, the second for work contacts or favorable tariff offers. Users of devices based Android often face a situation where they need to make a call not from the main card, but from the backup one, and do not know how to do this quickly. The Google operating system provides flexible management tools multi-SIM modesthat allow you to control the choice of line before each call or fix it for specific contacts.
However, the settings interface may differ depending on the shell manufacturer, be it pure Android, branded One UI from Samsung or MIUI from Xiaomi. Sometimes the system by default blocks the ability to select if priorities are not set, or the user accidentally activated a mode in which the second card is disabled for voice communication. Understanding the logic of operation Call Settings and knowing the hidden capabilities of dialing will help you avoid unnecessary costs and missed important calls.
In this article we will analyze in detail all the methods of switching between subscribers, starting from standard menus and ending with the use of USSD codes and engineering settings. You will learn how to set up automatic SIM card selection for different types of contacts and what to do if the operator selection button has simply disappeared from the dialing interface.
Basic setup of SIM card selection in the phone menu
The most obvious and reliable way to select the desired communication line is to use the built-in system settings. In most modern versions Android (starting from version 10), SIM card management is placed in a separate menu block. To access it you usually need to go to Settings → Connections → SIM card manager. Here you will see switches responsible for which card is used by default for mobile data, SMS messages and voice calls.
If you want the phone to ask you every time which SIM card to call from, you need to change the “Voice calls” parameter to “Always ask”. This action activates a pop-up window whenever you press the call button in your phone book or journal. This setting is most convenient for those who actively use both numbers equally and are afraid of forgetting to switch the line manually.
⚠️ Attention: On some budget segment models with a stripped-down firmware version, the “Always Ask” option may not be available. In this case, the system will use the card that is designated as the main one until you change the setting globally.
An alternative path to the settings is often hidden directly in the "Phone" application. Clicking on the three dots in the corner of the screen or the gear icon will take you to your local call settings. Look for the section Additional settings or Calls via SIM. Here the logic of operation is identical to the system menu, but access to it is faster, bypassing the general settings of the device.
⚠️ Attention: Shell interfaces from different manufacturers (Huawei, Honor, Oppo) may have a unique menu structure. If you do not find the described items, use the search inside the settings for "SIM" or "Calls".
Instant switching when dialing
For those who prefer not to change global settings, there is a more efficient method - selecting a SIM card directly at the time of dialing. When you enter numbers on a standard smartphone watch face, pay attention to the call button (usually a green handset). On dual-SIM devices, it is often divided into two parts or has a small icon next to it indicating the currently active card.
Pressing the main part of the button makes a call through the default card. However, if you press or hold the additional area of the button, the system will prompt you to select a second number. In some implementations, for example in Pixel or Moto, after entering the number, two SIM card icons with the captions “SIM 1” and “SIM 2” appear below it. Selecting one of them initiates a call through a specific operator.
This method is especially effective when you need to urgently call from a backup number, without wanting to delve into deep menus. It's also useful if you forget to change your settings back after an important work call. A visual hint on the dialing screen minimizes the risk of errors and accidental charges from the wrong balance.
Setting up calls for specific contacts
One of the most useful functions in the arsenal Android is the ability to assign a specific SIM card to a specific contact. This eliminates the need to select a number every time you call your parents, boss or courier. The implementation of this function depends on the Contacts application, which can be standard from Google or custom from the smartphone manufacturer.
To set up the link, open the card of the desired subscriber. At the top of the screen, next to the phone number or call button, there should be a SIM card icon or a selection menu. By clicking on it, you will see a list of available lines. Having selected the one you need, you will record this choice. Now, every time you call this person, the phone will automatically use the specified SIM card, ignoring the general default settings.
In some shells, such as MIUI or ColorOS, this function is implemented even more deeply. You can assign different SIM cards to different numbers of the same contact (for example, call your home phone from a landline, and call your phone from a personal SIM card). This requires care during the initial setup, but in the long run it saves a lot of time and nerves.
If the SIM card selection icon does not appear in the contact, try deleting the number and adding it again, saving the contact to the phone memory and not to your Google account, as synchronization sometimes hides local call settings.
It is recommended to periodically check critical contacts, especially if you change frequently devices or backing up data.
Using USSD codes and hidden menus
In addition to the graphical interface, there are text commands that allow you to control forwarding and network selection. Although a direct USSD code for switching a SIM card within the same phone is rare (since this is a function of the OS, not the operator), there are codes for checking the status of lines and controlling forwarding, which indirectly affects how calls are received and made.
For example, the code ##4636## opens the engineering testing menu, where you can see detailed information about each SIM card, signal strength and network type. In section Phone information You can forcefully disable the radio module of one of the SIM cards, which will force the phone to use only the remaining active line for all calls. This is a radical method, but it works flawlessly in critical situations.
*#06# - checking the IMEI of both SIM cards ##4636## - engineering menu (works on most devices)
**61*number# - setting up call forwarding when no response
It is also worth mentioning the forwarding control codes. If you want calls to one SIM card to go to another when the first one is unavailable, this can be configured through combinations of the form **61*forwarding_number#. This does not change the SIM card for outgoing calls directly, but helps manage the flow of incoming calls, creating the illusion of a single number.
Why may the engineering menu not open?
On some modern smartphones (especially Samsung and new Xiaomi) access to the menu ##4636## blocked by the manufacturer or telecom operator. In this case, you will need to install a third-party application such as Force LTE Only or obtain root access, which carries risks for the guarantee.
Third-party applications for managing calls
If the standard capabilities of the phone seem limited or inconvenient to you, the store Google Play offers many third-party solutions. Phone book look-alike apps and enhanced watch faces allow for flexible call rules that aren't available in stock firmware. They are especially useful for older smartphone models or devices with greatly reduced functionality.
Popular apps, such as Multi SIM Selector or advanced contact managers, add a quick switch button directly to the home screen or widget. This allows you to change the priority SIM card in one tap, without going into settings. Some apps even allow you to assign different ringtones depending on which SIM card is being called, which helps to instantly identify the line.
When choosing third-party software, pay attention to the permissions it requests. For call management to work correctly, the application requires access to phone, contacts and call log. Be careful with little-known developers, since access to call history is sensitive personal data.
| Application type | Main function | Setting up complexity | Security risk |
|---|---|---|---|
| Standard dialing | Basic SIM selection | Low | Absent |
| Contact managers | Binding SIM to subscriber | Medium | Low |
| Utilities switching | Quick change widgets | High | Medium |
| Engineering menus | Forced radio shutdown | High | High |
Third-party apps provide the most flexibility, but require careful developer review and may consume more battery power due to background work.
Troubleshooting and common problems
Often users are faced with a situation where the second SIM card stops making calls, although the balance is positive and there is a network. One common reason is a communication mode conflict. If mode is selected in the settings for the second SIM card 4G/LTE (data only), then voice calls through it will not be possible without VoLTE technology. In this case, you need to switch the network type to 3G/2G (auto) or activate VoLTE in the operator settings.
Another problem is the blocking of the second line due to tariff plan restrictions. Some operators prohibit the use of a second SIM card in the modem slot or impose restrictions on roaming. Check the terms of your tariff in your personal account. Also make sure that in the settings Call restriction there is no ban on outgoing calls for the selected SIM card.
- 📶 Check if the "Airplane" mode is enabled for only one of the SIM card slots.
- 💳 Make sure that the SIM card is not physically damaged and is correctly inserted into the tray.
- 🔄 Try rebooting the device after changing the network settings - this often solves problems with registering on the network.
- 📞 Check if all calls are forwarded to another number, which is why the call does not is initiated.
If all else fails, reset the network settings. This action will delete saved APNs and Bluetooth pairs, but will return communication settings to factory defaults, which often eliminates software glitches in SIM card selection. The path to the function usually lies through Settings → System → Reset settings → Reset Wi-Fi, mobile data and Bluetooth settings.
⚠️ Attention: Before resetting the network settings, write down your current access points (APN) for the mobile data, if your operator requires them to be configured manually, otherwise the Internet may stop working after a reboot.
Frequently asked questions (FAQ)
Is it possible to call from two SIM cards at the same time?
Technically, a smartphone can maintain an active connection with only one network for voice communication at a particular time (unless Dual VoLTE technology is used, which is still rare). You cannot talk on two lines in parallel through one speaker and microphone, but you can quickly switch between them or use the second line for the Internet while talking on the first.
Why does the choice of SIM card disappear when calling short numbers?
Many smartphones automatically route calls to emergency services (112, 102) and short service numbers through the main SIM card or the one with the best signal, ignoring the user's choice. This is done to guarantee connection in critical situations. It is usually impossible to change this behavior in standard settings.
Does the choice of SIM card affect the Internet speed during a call?
Yes, it does. If you call using SIM 1, and the Internet is configured on SIM 2, then in 3G/2G networks the Internet may temporarily turn off or become very slow. In 4G/LTE networks with VoLTE support, both channels can work simultaneously, but this depends on the capabilities of your operator and phone.
How to make the second SIM card only receive calls?
In the standard Android settings there is no direct “Incoming Only” function. However, you can set a restriction on outgoing calls in the Call settings → Call restrictionsection by turning on outgoing calls for the second SIM card. Or simply always select the first SIM card for outgoing calls using the “Always ask” function.